Composition and method for making water vapor permeable coated fabric



United States Patent COMPOSITION AND METHOD FOR MAKING WATER VAPOR PERMEABLE COATED FABRIC Norman J. Bertollo, Hawthorne, N.J., assignor to Inter- .clfleanical Corporation, New York, N.Y., a corporation 0 hio N0 Drawing. Filed Jan. 7, 1963, Ser. No. 262,813 4 Claims. (Cl. 117-63) This invention relates to a novel breathable coated fabric which provides an excellent leather substitute having both the hand or feel of leather and water vapor transmission or breathability approaching that of leather.

A good leather substitute should have several basic qualities: (1) a hand like that of leather, (2) a breathability approaching that of leather, (3) a good tear strength or resistance to tearing and (4) its top or exposed surface should have no visible pores.

I have discovered a novel coated fabric which is quite similar to leatherin these properties.

The novel coated fabric of this invention comprises a textile substrate, which may be a Woven or a non-woven textile, carrying a porous polymeric coating comprising the polyesterurethane elastomers described in US Patent 2,871,218. The porous coating has dispersed therein a flock.

In the description and claims which follow, all proportions are by weight unless otherwise stated.

When produced by the novel process which will be hereinafter described, the novel coated fabric of this invention, has a coating having an open celled sponge-like structure covered by a thin microporous skin in which coating flock is dispersed. While the sponge-like structure contributes to the overall soft leather-like hand of the fabric and the microporous skin contributes to the overall leather-likeappearance of the coated fabric, it is difficult to set forth in structural terms the other properties of this coated fabric which contribute to the composite visual and tangible effects very much like those of natural leather. These leather-like effects result from my novel method for making my coated fabric, particularly the inclusion of water and flock in the coating composition as well as the step of leaching by means of water.

The polyesterurethane of Patent No. 2,871,218 is dissolved in a suitable solvent, preferably methyl ethyl ketone or tetrahydrofuran. Cyclohexanone may also be used as a solvent.

The solution of the polymeric material is mixed with water to form a dispersion to which the flock is added and dispersed. Preferably, the water added is about from 5% to 30% of the weight of the solvent present and most preferably is from to of the weight of the solvent.

The flock may be any one of a wide variety of materials both natural and synthetic, e.g., nylon, polyester materials such as Dacron (polyethylene terephthalate), acrylic fibers such as Orlon (polyacrylonitrile), fibers of vinyl chloride copolymers, polyolefines such as polyethylene, cellulosic materials such as cellulose acetate and rayon as well as cotton, wool, ramie, flax and leather, e.g., nubless leather flock. Preferably the weight of the flock used is equal to about from 10% to 30% and most preferably from 20% to of the weight of the polyesterurethane employed.

It has been found that results are improved if the water being dispersed in the solution contains colloidal magnesium aluminum silicate which may be purchased commercially under the name Veegum. When present this additive preferably equals from 2% to 10% of the polyesterurethane in this dispersion.

3,222,208 Patented Dec. 7, 1965 The coated fabric may be colored either by using colpigment. The pigment is used in amounts preferably up to 10% of the weight of the polymer.

The coating composition is applied to the substrate at a wet coating thickness preferably from about 40 to 150 mils. The substrate is preferably a woven textile, although non-woven textiles are utilizable. Cotton textiles have produced good results. However, any of a wide variety of natural and synthetic textiles would give satisfactory results, e.g., nylon, polyesters such as Dacron materials, materials of acrylics such as Orlon, vinyl chloride copolymers, cellulosics such as rayon and cellulose acetate as well as natural materials such as cotton, Wool, ramie, hemp and linen.

The coated fabric is then leached. It is preferable that the leaching step be commenced as soon as possible after the coating step. Leaching is accomplished by placing the coated fabric into a current of flowing water, preferably cold water at 12 to 20 C. This may be done by placing the coated fabric into a tank of moving water from which water is being continuously removed and into which fresh water is being continuously fed. I have found that during the leaching step, solvent is removed from the coated fabric. However, this is clearly not the only effect of the leaching step. Such other effects have not been definitely ascertained but it is known that they contribute to the leather-like hand and breathability of the coated fabric. For example, I have found that when the solvent is removed by evaporation rather than leaching, the resulting coated fabric has a stiff hand unlike that of leather and has very low water vapor transmission. Even where the wet coated fabric is permitted to partially airdry prior to leaching the hand and the water vapor transmission of the coated fabric are significantly downgraded.

After leaching is completed, the coated fabric is permitted to dry, suitably by air drying. However, the drying may also be conducted at higher temperatures.

It should also be understood that the coated fabrics of this invention may be further overcoated with top coats which do not appreciably reduce water vapor transmission.

The following examples will illustrate the practice of this invention:

Example I A polyesterurethane is prepared following the procedure set forth in US. Patent 2,871,218, col. 4, lines 13 to 27. A mixture of 1447 g. (1.704 mols) of hydroxyl poly (tetramethylene adipate), molecular weight 849, hydroxyl number 130.4, acid number 0.89, and 109.6 g. (1.218 mols) of butanediol-l,4 is melted in a four liter kettle and stirred with a spiral ribbon stirrer for about 20 minutes at a pressure of 5 to 6 mm. at to C. To this mixture, there is added 730 g. (2.92 mols) of diphenyl methane-p,p diisocyanate. This mixture is stirred for about 1 minute and is then poured into a lubricated one gallon can which is promptly sealed with a friction top and the can placed in a C. oven for 3.5 hours. The product is then cooled.

To 228 parts of a solution of said product polyesterurethane in methyl ethyl ketone (35% solids by weight), there are added 80 parts of a 6% aqueous solution of colloidal magnesium aluminum silicate and the mixture is stirred to form a dispersion which is creamy light tan in color. To the resulting mixture, there are added about 20 parts of a rayon flock having an average fiber length of about .03 inch while the mixture is continuously stirred. The mixture is coated at a thickness of Vs inch onto a cotton sheet having a weight of 0.002 ounce per square inch. As soon as possible after coating, the coated fabric is leached with water. This is accomplished, for

example, by placing a piece of coated fabric 1.5 sq. ft. in area in a tank containing about 2 gallons of water and then flowing water at about 16 to 20 C. through a tank at the rate of about /3 of a gallon per minute to replace the water in the tank. The leaching is continued for 15 minutes. The resulting coated fabric after air drying at room temperature has a hand closely resembling that of a leather and a water vapor transmission or breathability approaching that of leather. Water vapor transmission when measured according to ASTM-E96-53T shows that the water vapor transmission of the product is about 37 g./square meter/24 hours at a 100% relative humidity and a temperature of 100 F. while natural leather has a water vapor transmission of from about 80 to 150 g./ square meter.

Example ll Example I is repeated using the same ingredients, proportions and conditions except that in place of the polyesteruret-hane used in Example I, a polyesterurethane made in accordance with the description set forth in US. Patent 2,871,218, col. 5, lines 19-28 is used. The resulting coated fabric has properties very close to those described for the product of Example I.

While there have been described what is at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A method for making a water vapor permeable coated fabric comprising dispersing flock in a mixture of water having dissolved therein colloidal magnesium aluminum silicate and a solution in an organic solvent selected from the group consisting of methyl ethyl ketone, tetrahydrofuran and cyclohexanone of an essentially linear polyesterurethane elastomer which is the reaction product obtained by heating a mixture comprising as essential polyesterurethane forming ingredients (1) one mol of an essentially linear hydroxyl terminated polyester of a saturated aliphatic glycol having from 4 to carbon atoms and having hydroxyl groups on its terminal carbon atoms and a material selected from the group consisting of a dicarboxylic acid of the formula where R is an alkylene radical containing from 2 to 8 carbon atoms and its anhydride, said polyester having an average molecular weight between 600 and 1200 and having an acid number less than 10, and (2) from 1.1 to 3.1 mols of a diphenyl diisocyanate having an isocyanate group on each phenyl nucleus in the presence of (3) from about 0.1 to 2.1 mols of a saturated, aliphatic'free glycol containing from 4 to 10 carbon atoms and having hydroxyl groups on its terminal carbon atoms, the molar amount of said polyester and said free glycol combined being essentially equivalent to the molar amount of said diphenyl diisocyanate whereby there are essentially no groups of the clas consisting of isocyanate and hydroxyl groups in said reaction products, then applying said dispersion to the surface of a textile substrate and leaching said coated textile with water to remove the solvent.

2. The method of claim 1 wherein the substrate is a cotton fabric.

3. The method of claim 1 wherein the coated textile is leached at a temperature of from 12 to 20 C.

4. A coating composition comprising flock dispersed in a mixture of water having dissolved therein colloidal magnesium aluminum silicate and a solution in a solvent selected from the group consisting of methyl ethyl ketone, tetrahydrofuran and cyclohexanone of polyesterurethane elastomer produced by heating a mixture comprising as essential polyesterurethane forming ingredients (1) one mol of an essentially linear hydroxyl terminated polyester of a saturated aliphatic glycol having from 4 to 10 carbon atoms and having hydroxyl groups on its terminal carbon atoms and a material selected from the group consisting of a dicarboxylic acid of the formula where R is an alkylene radical containing from 2 to 8 car-- bon atoms and its anhydride, said polyester having an average molecular weight between 600 and 1200 and having an acid number less than 10, and (2) from about 1.1 to 3.1 mols of a diphenyl diisocyanate having an isocyanate group on each phenyl nucleus in the presence of (3) from about 0.1 to 2.1 mols of a saturated, aliphatic free glycol containing from 4 to 10 carbon atoms and having hydroxyl groups on its terminal carbon atoms, the molar amount of said polyester and said free glycol combined being essentially equivalent to the molar amount of said diphenyl diisocyanate whereby there are essentially no unreacted groups of the class consisting of isocyanate and hydroxyl groups in said elastomer.

References Cited by the Examiner UNITED STATES PATENTS 25,192 8/1859 Goodyear 117135.5 2,490,001 11/ 1949 Jayne et al. 26077 2,622,307 12/ 1952 Cogovan et al 117-169 2,751,363 6/1956 Martin 260-40 2,871,218 1/ 1959 Schollenberger 26032.6 2,929,800 3/1960 Hill 26037 3,100,721 8/1963 Holden 117-135.5

WILLIAM D. MARTIN, Primary Examiner.

RICHARD D. NEVIUS, Examiner. 

1. A METHOD FOR MAKING A WATER VAPOR PERMEABLE COATED FABRIC COMPRISING DISPERSING FLOCK IN A MIXTURE OF WATER HAVING DISSOLVED THEREIN COLLOIDAL MAGNESIUM ALUMINUM SILICATE AND A SOLUTION IN AN ORGANIC SOLVENT SELECTED FROM THE GROUP CONSISTING OF METHYL ETHYL KETONE, TETRAHYDROFURAN AND CYCLCOHEXANONE OF AN ESSENTIALLY LINEAR POLYESTERURETHANE ELASTOMER WHICH IS THE REACTION PRODUCT OBTAINED BY HEATING A MIXTURE COMPRISING AS ESSENTIAL POLYESTERURETHANE ELASTOMER WHICH IS THE REACTION PRODUCT OBTAINED BY HEATING A MIXTURE COMPRISING AS ESSENTIAL POLYESTERURETHANE FORMING INGREDIENTS (1) ONE MOL OF AN ESSENTIALLY LINEAR HYDROXYL TERMINATED POLYESTER OF A SATURATED ALIPHATIC GLYCOL HAVING FROM 4 TO 10 CARBON ATOMS AND HAVING HYDROXYL GROUPS ON ITS TERMINAL CARBON ATOMS AND A MATERIAL SELECTED FROM THE GROUP CONSISTING OF A DICARBOXYLIC ACID OF THE FORMULA 